Problem: $ { \left[\begin{array}{rr}{-1} & {1} \\ {4} & {2}\end{array}\right]+\left[\begin{array}{rr}{4} & {0} \\ {-2} & {-1}\end{array}\right] = {?} } $
Solution: To find the sum of two matrices, add the corresponding items between each matrix. ${\left[\begin{array}{rr}{-1}+{4} & {1}+{0} \\ {4}+{-2} & {2}+{-1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{3} & {1} \\ {2} & {1}\end{array}\right]}$